The impression area of a cylinder is solely along the line where it’s in contact with the form, as opposed to the full platen of a C&P, so your ability to maximize your form/bed ratio is better. The Challenge/Vandercook type will be much slower than a C&P, though, so not so good for large jobs. You’ll feel like your arm is falling off!

I don’t use a C&P, so I can’t say much about their registration abilities. My Heidelberg platen is great for it. I’ve done some very fine registration on my SP-20, so it can certainly be done. It’s a hand-cranked press, so take it slow and you can do many things with it.

I’ve had issues with registration on vandercooks and am still trying to nail down the exact problems. I know tight registration can be done, especially if you make sure you carefully feed the paper the same way, holding the paper to the cylinder in the same way with the same pressure. Some problems come up from printing with enough impression to stretch the paper, in which case registering the second color can be difficult/impossible.

Vandercook’s print best when the sheet is long enough to be held to the cylinder, so it’s common to print on one half the sheet, then turn it around and print on the other half, but if you get lazy and print one half right after the other, then it’s hard to feed the two sides the same exact way because you don’t want to smudge the first half while holding the paper tight for the second half!

I’ve been trying to figure something out recently, where I’m being careful to feed exactly the same every time, and my crop marks are moving a point or two left or right. It was a job where I was printing on the back as well, so when I turned the paper over I used a gauge pin in some tympan taped down to the feedboard to keep the registration edge consistent, and on that size, the printing was totally consistent. The side-gauge on my vandercook has a springy action but strong enough that I can’t imagine I’m pushing it when I feed paper against it. It seems worse when I print with thick papers and I wonder if it’s just not pushing against the gauge consistently, though I pay close attention to it.

Does your side guide’s gauge have a foot on it, to guide the paper to the same position? If you’re not sure what I mean, look at the guide and there should be a piece of metal sticking out that kind of lowers the paper towards the feeboard so it contacts the same spot.

If you don’t have this foot there….. Sometimes the paper might sit a bit higher on the gauge, and if it weren’t level vertically, this could cause a bit of a shift in register.

Widmark,
Also make sure the paper is truly cut square. To do that flip the sheet over and put two sheets face to face.
If they are not square you will see one is: longer, taller, wider, shorter, than the other. In which case you I’ll have a hard time getting back to front registration regardless of the press you use.
Steve V

Steve, that’s something I’m aware of, and is often the case (when I’m lazy) but not the issue here. The frustations I have are just on the first side, having inconsistencies. And it’s not even the far out marks on the tail of the paper which could fishtail on a vandercook, but the ones closest to the grippers, which seems to me to be more an issue of feeding rather than holding while printing. It just shocked me that when I switched to the back using a different registration guide, every print was spot on.

There is no hard or fast rule for what kind of work can and cannot be run on a platen press. I have a preference for the cylinder press for just the reasons Jonsel mentions, but I’ve had good success running full 11”x17” text forms on a 12”x18” C&P Craftsman. Makeready is required no matter which press you use, I just find it a bit easier on the cylinder press.

When hand-feeding sheets to the press, neither type of press has an advantage from the point of registration accuracy. It is mostly in the hands of the operator.

If you are comfortable with the 10”x15” C&P, ands get the results you want, you should be able to obtain the same with the larger press on larger format work.

Widmark:

Make certain you sheets aren’t pulling slightly out of the grippers as they are being fed around the cylinder. It might be good to set up long crossed rules and run some sheets repeatedly through with contrasting color so you can see exactly which direction the image is moving and what it is that might be at fault.

pretty sure they’re not. In fact I’m having another issue where suddenly one of my grippers seems to be gripping way more than it used to, to the point that it’s leaving really bad marks on my paper, while the other grippers aren’t. I’ve never adjusted the gripper tension on my press (a 219os) but plan on looking into that. Probably not coincidently, there’s a screw that’s even with the gripper that looks like it has a lot of damage from somebody working it too hard/much, in ways that the other screws don’t.

It’s just strange that this started becoming an issue after a year or two. No problem with my last few jobs which were all cut down from larger sheets. The last time I printed on paper already cut to size, I hacked together a few sheets of paper on that gripper to protect the paper and it helped. Not a permanent solution though.